One vertex per element, one color per generator, with an edge from x to x·s.
(1,2,4,5)(3,7,8,6)(9,10)(11,15)(12,16)(13,18)(14,20)(17,26)(19,21)(22,31)(23,33)(24,30)(25,32)(27,35)(28,37)(29,38)(34,36)(39,40)(2,5)(6,7)(9,11,21,22,14,25,13,24)(10,15,19,31,20,32,18,30)(12,23,36,37,27,39,26,38)(16,33,34,28,35,40,17,29)(10,16)(11,22)(12,26)(13,21)(15,28)(17,19)(18,34)(20,35)(24,25)(27,36)(29,32)(30,40)(31,33)(37,38) involution — undirected(1,3,4,8)(2,6,5,7)A Cayley diagram is a choice, not a fact about the group. Another drawing of this group — in a book, or on a different generating set — may look nothing like this one.